adding checkout step

.gitea/workflows/build.yaml

@@ -10,6 +10,10 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - run: echo "The job was automatically triggered by a ${{ gitea.event_name }} event on branch is ${{ gitea.ref }} and your repository is ${{ gitea.repository }}."
+      - name: checkout main
+        uses: actions/checkout@v4
+        with:
+          ref: main
       - name: Build package
         run: |
           ./mvnw clean package -Pproduction